fix: Avoid importing feast.feature_store at mcp_server import time

larrysingleton007 · ntkathole · commit ddb2e9ad54d0 · 2026-07-23T15:41:21.000+05:30
mcp_server used a module-level `from feast.feature_store import FeatureStore`
solely for a type annotation on add_mcp_support_to_app. Because the
feast.infra.mcp_servers package __init__ eagerly imports mcp_server, importing
the package pulled in the entire feature_store import graph. Under parallel
unit-test collection (pytest -n) this intermittently raced with an in-progress
feature_store import and failed collection of test_mcp_server.py with
`KeyError: 'feast.infra.mcp_servers.mcp_server'`.

Move the import under TYPE_CHECKING and use a forward reference, so importing
mcp_server no longer triggers the feature_store graph. Public API and the
annotation are unchanged.

Signed-off-by: Larry Singleton &lt;166439969+larrysingleton007@users.noreply.github.com&gt;
diff --git a/sdk/python/feast/infra/mcp_servers/mcp_server.py b/sdk/python/feast/infra/mcp_servers/mcp_server.py
@@ -6,9 +6,10 @@
 """
 
 import logging
-from typing import Any, Dict, Optional, Set
+from typing import TYPE_CHECKING, Any, Dict, Optional, Set
 
-from feast.feature_store import FeatureStore
+if TYPE_CHECKING:
+    from feast.feature_store import FeatureStore
 
 logger = logging.getLogger(__name__)
 
@@ -97,7 +98,9 @@ def _patch_fastapi_mcp_schema_resolver() -> None:
         pass
 
 
-def add_mcp_support_to_app(app, store: FeatureStore, config) -> Optional["FastApiMCP"]:
+def add_mcp_support_to_app(
+    app, store: "FeatureStore", config
+) -> Optional["FastApiMCP"]:
     """Add MCP support to the FastAPI app if enabled in configuration."""
     if not MCP_AVAILABLE:
         logger.warning("MCP support requested but fastapi_mcp is not available")
